Restoring 365 mailbox - hybrid (We are preparing a mailbox for the user)

Question

Hello,

We are using a hybrid set-up for 365/Azure and I've got into a bit of a mess with an account that I'm hoping someone might be able to assist with.

I had a problem with an account that had the wrong onmicrosoft.com address and Azure wasn't picking up the corrected address after changing it on-premise exchange so I moved the user's on-premise AD account out of the sync scope yesterday, waited for it to sync again and then moved it back. This resulted in the mailbox getting deleted from 365 but the Azure account was still there. I tried to restore it from the admin centre but it wouldn't let me due to a conflict with e-mail address on the existing account (that was being synced from on-premise).

I deleted the existing AD account from on-premise, let it sync and it let me restore the account. Of course this account wasn't syncing with on-prem.

I then read the guide here (Restoring a user in a hybrid deployment) which states that I need to create a new mailbox for the user first and then restore the soft-deleted account into it-

https://learn.microsoft.com/en-us/exchange/recipients-in-exchange-online/delete-or-restore-mailboxes

So I deleted the account I'd just restored from the admin centre. I think my mistake was removing the license before I deleted it as from what I've read, this performs a hard-delete.

I then re-created the on-premise AD account and mailbox and migrated it to 365.

I was then unable to get the GUID of the old mailbox (I assume because it had been hard rather than soft deleted) so was unable to restore it using the method in that guide. The plan was to restore it again from the admin centre (which it let me do), give it a license so it restored the cloud mailbox and then soft-delete it so that I can get the GUID and continue to follow that guide. The problem I have is that now I've restored the account again and given it a license, it's not created the mailbox.

If I look on the 'Mail' tab on the account I restored, it says 'We are preparing a mailbox for the user.' but it's been saying that since 20.30 last night.

Answer 1

@Jon234

I want to confirm with you, how did you create your mailbox in the first place? Sync AD account to Azure AD, then enable license on it enable mailbox? Or migrate Exchange on-premises mailbox to Exchange online?

If this mailbox is created by enable license, you cold try to enable license to this AAD account again to check whether could bring this mailbox back. Due to you delete and recreate AAD account before, I think there may exist issue with it.

If this mailbox is a migrated mailbox, you can check the delete mailbox from this place, if this mailbox show in this place, you could try to restore it, if this mailbox doesn't show in this place, you may cannot restore this mailbox:

---

If the response is helpful, please click "Accept Answer" and upvote it.
Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread.

Answer 2

Thank you for your reply. The mailbox was initially created by migrating the Exchange on-premises mailbox to Exchange online.

I don't have the option to view deleted mailboxes in the Exchange admin centre. See screenshot below.

Answer 3

So I deleted the account I'd just restored from the admin center. I think my mistake was removing the license before I deleted it as from what I've read, this performs a hard-delete.

I do this test in my lab, you could check whether the steps are the same as yours. If it is same as yours, you will cannot recover this old mailbox on Exchange online.

If you remove a license from a migrated mailbox, this mailbox will show as mail user under "Contacts"(From this step, if you assign license back to this mailbox, data will back). I try to delete this mail user, but it is cannot deleted.

Do you mean remove this AD account to an out of sync OU? If so, this AAD account will show in Deleted users, mailboxes will not show in "Soft Deleted" list. From this step, if you resync this AD account, you could also assign license back to this account, this mailbox can also show up.

Based on your description, you delete this the AD account and recreate a new one. The new synced AD account will cannot connect to the original mailbox. It is a new mailbox which use the same email address as the old mailbox.